JPH05165317A - Development device - Google Patents

Abstract

PURPOSE:To prevent an image defect due to the influence of a foreign matter such as paper powder mixed with a collected developer in a cleanerless process (development and cleaning system) while eliminating a sleeve ghost which is frequently generated in a single-component development system. CONSTITUTION:Toner T in a toner storage part 2 is supplied to a developing roller 6 through a toner conveyor roller 7 to visualize a latent image on a photosensitive drum 5. Toner T on the developing roller 6 which is not consumed for the development is carried to the toner carrier roller 7 associated with the rotation of the developing roller 6, and moved onto the toner carrier roller 7, which rotates to convey the toner to the side of a toner peeling member 8; and toner T sticking on the toner conveyor roller 7 is peeled off to specific effective length and collected in the toner storage part 2, and then used again for development together with other toner T.

Description

Detailed Description of the Invention

 [Object of the Invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device for visualizing an electrostatic latent image in an electrophotographic device or an electrostatic recording device, and in particular, a developing device capable of obtaining a high quality image by using a one-component developer. Regarding the device.

[0002]

2. Description of the Related Art In recent years, a developing system using a one-component developer has been put into practical use.

This is different from the developing system using a two-component developer consisting of a toner and a carrier, in which a developer carrier, a magnet roller, a toner density control device, etc. are not required, and the device is small in size. It has the features of being priced and fixed price. Conventionally, as one of the developing methods using a one-component developer, a pressure developing method (Impression Deveropment)
It has been known.

This method is characterized in that an electrostatic latent image and a toner carrier having a thin layer of toner particles as a developer are brought into contact with each other at a relative peripheral velocity of substantially zero, and USP-
3,152,012, USP-3,731,148, JP-A-47-1
No. 3088 and Japanese Patent Laid-Open No. 47-13089. These have many advantages such that the device can be simplified and miniaturized, and the toner can be easily colored because no magnetic material is required.

In this pressure developing method, since the toner carrying member is pressed or brought into contact with the electrostatic latent image to perform development,
It is necessary to use a developing roller having appropriate elasticity and conductivity as a toner carrier. In particular, when the electrostatic latent image carrier is a rigid body, it is an essential condition that the developing roller is made of an elastic body in order to avoid damaging it. In addition, as another one-component developing method, USP is used.
There are non-contact development methods described in US Pat. No. 3,866,574 or USP-3,893,418.

In this method, the developer layer is brought close to the electrostatic latent image and an alternating electric field is applied to the gap to leap the developer (toner) for development. -It is common that La is made of a rigid body.
By the way, it is generally known that in these one-component developing methods, an image defect due to a history image called a sleeve ghost may be exhibited.

The cause of this sleeve ghost is mainly due to the toner layer forming characteristics on the developing roller. That is, during development, if the toner layer thickness or the charge amount is not restored to the same condition as the other portions by the time the portion where the toner is transferred to the electrostatic latent image side is subjected to the next development, both This is caused by a density difference due to a history (memory) difference.

Further, it has been found that when such a developing device is applied to a so-called developing / cleaning process (cleanerless process), a new problem occurs. This is because foreign matter such as paper dust mixed with the developer collected by cleaning and separated from the transfer paper is collected and mixed in the developing device at the same time, and accumulated in the developing roller that is the developer conveying means. The problem is that the device replacement or cleaning is inevitable due to a defective image even though the developer remains. For this reason, conventionally, the following means have been proposed as a means for solving the problem of using the developing device alone, and the solution has been made for the time being.

(1) A history difference is eliminated by bringing a scraping member such as a blade or a sponge roller into contact with the developing roller to remove all the toner remaining on the developing roller. (2) A bias voltage is applied to a conductive roller or the like to bring it close to the developing roller and peel the entire surface from the developing roller.

What is common to both of these is that the history difference due to the development pattern is erased by temporarily peeling the entire surface of the roller after the toner has been subjected to development, which is considered from the cause of occurrence. Is reasonable.

[0011]

However, it has been found that any of the above-mentioned means for solving the problems has problems or is not sufficient as it is.

First, it is not preferable to bring a member such as a blade into contact with the developing roller, because the developing roller is liable to be damaged or the toner is partially adhered to the developing roller.
This is particularly remarkable when an elastic roller made of rubber or resin is used as a developing roller, and it is not suitable to use it as a peeling member. From this point of view, it is considered preferable to use a roller-shaped scraping member as the developer separating member from the elastic developing roller. However, even if such measures are taken, it has been occasionally found that when 1000 to 2000 sheets are printed, uneven fogging occurs in the image.

As a result of investigating the cause of this, the developing roller accumulates in the vicinity of the peeling member and gradually becomes a high concentration, and the undeveloped new developer and the charged old developer (recovered developer) are mixed with each other. Therefore, it was found that the unevenness was caused in the development and an image defect was exhibited because the ink was re-supplied. It was found that this is caused by the difference in the history of the developers in the developing container, as in the case of the history image (sleeve ghost) generated on the developing roller.

Further, when such a developing device is used as the developing / cleaning device as described above, not only the developers having different charging histories are re-supplied, but also the paper dust (talc) contained in the transfer paper. It has been found that foreign matter such as (or kaolin) accumulates on the developing roller and the peeling roller and causes charging troubles, which significantly shortens the life of the apparatus.

The present invention has been made based on the above circumstances, and eliminates the sleeve ghost that often occurs in the one-component developing system, and at the same time, removes paper dust or the like mixed in the collected developer in the cleanerless process (developing and cleaning system). An object of the present invention is to provide a developing device that prevents image defects due to the influence of foreign matter.

[0016]

As a first means for solving the above-mentioned problems, the present invention visualizes a latent image on an image bearing member with a one-component developer and at the same time develops a residual developer on the image bearing member. And a developing device main body having a developer accommodating portion for accommodating a one-component developer, and a developing device main body and a developing portion of the image carrier facing the developing portion. A developer transporting unit that is arranged and is capable of supplying a developer to the developed portion during the developing process and receiving the residual developer on the image bearing member during the cleaning process, and the developer transporting unit on the surface of the developer transporting unit. Developer layer forming means for forming a thin layer of the component developer, and rotatably provided in the developing device main body for supplying the developer in the developer accommodating portion to the developer conveying means and for developing the developed portion. The current on the developer transport means that has passed The developer transfer means for receiving the developer and the developer attached to the developer transfer means in contact with the developer transfer means are peeled off over a predetermined effective length and collected in the developer storage section. A developer peeling means is provided.

As a second means, there is provided a developing device for visualizing a latent image on an image bearing member with a one-component developer,
A developing device main body having a developer accommodating portion for accommodating the one-component developer, and a developer disposed in the developing device main body so as to face the developed portion of the image carrier and supply the developer to the developed portion. Rotatably driven developer conveying means, developer layer forming means for forming a thin layer of the one-component developer on the surface of the developer conveying means, and the developer rotatably provided in the developing device main body. A developer transfer means for supplying the developer in the accommodating section to the developer transfer means and a developer on the developer transfer means that has passed through the development target portion, and a developer transfer means for contacting the developer transfer means. It is configured to include a developer peeling unit that peels the developer adhering to the developer transfer unit over a predetermined effective length and collects the developer in the developer storage unit.

[0018]

According to the developing device of the present invention, the developer accommodated in the developer accommodating portion is supplied to the developer conveying means by the developer transferring means. Then, the developer supplied to the developer transport means is transported to the image carrier side by the rotation of the developer transport means, and a thin layer of the one-component developer is formed on the surface of the developer transport means by the developer layer forming means. It is formed. Then, when the thin layer of the developer faces the developed portion of the image carrier, the developer electrostatically adheres to the latent image and is visualized.

The developer that has not been used for development is carried to the developer transfer means by the rotation of the developer transfer means, and the developer transfer means moves to the developer transfer means and the developer transfer means. Is conveyed to the developer peeling means side with the rotation of the developer, where the developer adhering to the developer transferring means is peeled off over a predetermined effective length and collected in the developer accommodating portion, and again the other developing It is used for development together with the agent.

That is, since the developer on the developer conveying means that has not been used for development is once removed and collected in the developer accommodating portion, it is not short-circuited and conveyed to the developer layer forming means side. The development history on the developer conveying means can be completely erased, and a good developing operation without developing failure called a sleeve ghost can be performed.

Further, even if foreign matter such as paper dust separated from the transfer paper is mixed with the developer and collected in the developing device, the foreign matter is collected together with the developer in the developer accommodating portion and accumulated in the developer conveying means. This prevents the developer layer forming device from normally charging the developer, and prevents the device from being replaced or cleaned due to an image defect even though the developer remains. It Therefore, the present invention can be applied to a developing / cleaning process (cleanerless process).

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a sectional view of a developing device 1 of the present invention.

The developing device 1 uses a non-magnetic toner T (hereinafter simply referred to as toner T) as a developer.
A developing device main body 4 is integrally formed with a toner hopper 3 whose inside serves as a toner storage portion 2 as a developer storage portion.

The developing device main body 4 is in a state in which a portion facing the photosensitive drum 5 as an image carrier is opened, and the photosensitive drum 5 is brought into contact with the photosensitive drum 5 in the vicinity of the opening. There is provided a developing roller 6 as a developer conveying means that rotates in a direction of the arrow (the direction of the arrow) with respect to the rotating direction of. The developing roller 6 has conductivity and elasticity.

At the rear side of the developing roller 6, the toner accommodating portion 2 is provided.
Toner T between the developing roller 6 and the portion corresponding to the bottom of
A toner transfer roller 7 is provided as a developer transferring means for transferring the toner.

Further, on the rear side of the toner transfer roller 7,
A toner peeling member 8 as a developer peeling means having a net-like body 8D described later is provided between a holder portion 3A fixed to the bottom of the toner hopper 3 and an upper partition plate 3B forming a part of the toner hopper 3. And is pressed against the rear side of the toner transfer roller 7 in the longitudinal direction (length effective for development).

Located above the developing roller 6 in the developing device main body 4, the toner carrying amount by the developing roller 6 is regulated, and the toner T is transferred to the surface of the developing roller 6. A blade 9 is provided as a developer layer forming means for forming a thin layer. Recovery to the state where it contacts the lower surface side of the developing roller 6
A blade (mylar film) 10 is provided.
A mixer as stirring means is provided in the toner accommodating portion 2.
11 is provided to stir Toner-T.

The developing device 1 in this embodiment is provided with a developing roller 6 having conductivity and elasticity. A thin layer of toner T is formed on the surface of the developing roller 6 to form an electrostatic latent image. The development is performed by bringing the surface of the body drum 5 into contact with the surface of the body drum 5, and a developing method that does not require a developer carrier, a magnet roller, a toner concentration control device, or the like and can be downsized and cost-effective. Next, the main components of the developing device 1 according to the present invention will be described in detail. First, the developing roller 6 as the developer transporting means will be described.

The first characteristic required of the developing roller 6 is
It has conductivity and elasticity, and the simplest structure that satisfies this is a combination of a metal shaft and a conductive rubber roller, but the toner T is conveyed while being pressed against the surface of the developing roller 6. Surface smoothness is required.

Therefore, in this embodiment, as shown in FIGS. 1 and 2, a two-layer structure in which the elastic layer 6B and the surface conductive layer 6C are sequentially formed around the metal shaft 6A is adopted.

As the elastic layer 6B, there are two types of conductive layer and non-conductive layer.
A conductive material is preferable in consideration of peeling and scratches on the surface. Since the elastic layer 6B is in pressure contact with the blade 9 and the photosensitive drum 5, a large load is required to obtain a predetermined nip when the rubber hardness is large, which in turn increases the torque of the developing device.

Further, the permanent strain (%) defined by JISK6301 caused by packing and left for a long time also becomes a problem, and when it exceeds about 10%, unevenness of the developing roller cycle occurs in the image, so that the elastic body The compressive strain (%) of the layer 2b should be 10% or less, preferably 5% or less. The relationship between the rubber hardness and the permanent set (5) generally tends to decrease as the rubber hardness increases, so that the balance with the material is important.

After being deformed by the blade 9, the developing roller 6 is sent to the developing portion of the photosensitive drum 5, but if it is deformed, it will affect the development. Therefore, the deformation must be recovered by then. I have to. Therefore, the elastic layer 6B has a rubber hardness of 35 ° or less, preferably 30 ° or less, and the conductive layer 6C has a rubber hardness of 35 ° or less, preferably 30 ° or less. The conductive layer 6C is formed by applying a conductive urethane-based paint to the surface of the elastic layer 6B by spray coating or dipping and directly contacts the toner T or the photosensitive drum 5, so that a plasticizer, a vulcanizing agent, It must be such that the toner T and the photosensitive drum T are not contaminated by the exudation of process oil or the like.

The surface smoothness of the conductive layer 6C is 3
It is preferably not more than 5 μm Rz, and if it is more than 5 μm Rz, a pattern of surface irregularities is likely to appear in the image. In order to realize a smoothness of 3 μm Rz, a conductive layer 6C having a sufficiently large film thickness is attached to the elastic layer 6B, and a predetermined outer diameter is obtained by post-processing (polishing).
Although it may be considered to finish the surface with a rough surface, the cost becomes high, so that the surface roughness of the elastic layer 6B, the film thickness of the conductive layer 6C, and the viscosity of the coating material are optimally selected in order to realize without post-processing. It is to be.

That is, the lower the viscosity of the coating material and the larger the surface roughness of the elastic layer 6C, the surface conductive layer 6 is formed.
The film thickness of C must be increased. Regarding the viscosity of the paint for forming the conductive layer 6C, it is necessary to use the same paint by changing the viscosity (changing the dilution amount) according to the method of applying the paint to the surface of the elastic layer 6B.

The required characteristics of the developing roller 6 are that the elastic layer 6B has a rubber hardness (JIS-A) of 35 ° or less and an elongation of 25.
0 ~ 500%, resistance value 1 × 10 ⁷ Conductive silicone rubber of Ω · cm or less is used, and the conductive layer 6C is made of conductive polyurethane paint, for example, product name “SPAREX” manufactured by Nippon Miractron Co., Ltd. Resistance value 10 ⁴ ~ 10 ⁶ Ω · cm, elongation 1
For example, the developing roller 6 as a whole has a rubber hardness of about 30 to 40 °.

An elastic layer 6 having a surface roughness of 5 to 10 μm
Film thickness of 50 to 120 μm for B by spray coating
By forming the conductive layer 6C to a certain extent, the developing roller 6 having a surface roughness of about 3 μm Rz can be realized and a good image can be obtained.

In this embodiment, the developing roller 6
As the metal shaft 6A, a conductive silicon rubber as the elastic layer 6B and a conductive polyurethane coating as the surface conductive layer 6C is used as the metal shaft 6A. However, if the above-mentioned characteristics are satisfied, Of course, it is not limited thereto. Next, the toner transfer roller 7 as a developer transfer means will be described.

The toner transfer roller 7 is a metal shaft 7A.
Around 10 ⁹ Density 0.45g / cm ² with conductivity of about Ω · cm or less , A flexible foamed polyurethane foam layer 7B having a cell number of 50 to 60 cells mm is provided, the rotation speed is about 0.5 to 4 times that of the developing roller 6, and the rotation direction is in the against direction (preferred rotation of both The direction is indicated by an arrow, but is not limited to this.) By applying a bias voltage having the same potential as the developing roller 6 or a voltage higher by about 100 V by the bias power source V ₁ , the toner T moving function is improved. It works, and a good image can be obtained.

The urethane foam layer 7B is not limited to this, and can be replaced with other materials such as other rotating brushes and foamed silicone rubber that meet mechanical requirements or electrical characteristics. Is.
Since this bias voltage contributes to the transfer amount of toner, it is desirable to confirm and adjust it experimentally. Next, the toner peeling member 8 as the developer peeling means will be described in detail with reference to FIG.

The toner peeling member 8 has a function to slide the toner T from the toner transfer roller 7 by slidingly contacting the toner transfer roller 7 which rotates the edge portions of the mesh of the mesh 8D. Have

The toner peeling member 8 is made of a material such as stainless steel or polyester and has a thickness of 0.03 to 0.1 mm.
A large number of openings 8B and 8C that can maintain the mechanical strength are provided in the upper and lower portions of the contact portion with the developing roller 6, which is made of a film-shaped member 8A.

Further, a mesh body 8D made of a thin wire made of nylon fiber, stainless steel, steel or the like is formed at the contact portion with the toner transfer roller 7, and the mesh body 8D has a thickness of 2 to 10 mm. The width of the developing roller 2 is rubbed along the longitudinal direction. The mesh size of the mesh body 8D is about 50 to 200 mesh, and in any case, it is preferable that the fine wire forming the mesh is as thin as possible. In practice, a diameter of 10 μm to 50 μm is easy to use and easy to maintain.

The toner peeling member 8 as described above is stretched in the developing device 1 and rubbed against the toner transfer roller 7 while applying an appropriate pressure to the toner transfer roller 7.
The mesh 8D scrapes the upper toner layer one after another. The toner T scraped off passes through the mesh and floats on the mesh 8D. Here, the toner is gradually swept up by the mixer 11 shown in FIG. 1 and is carried into the toner accommodating portion 2 and mixed with another toner T.

The toner T thus peeled off is supplied to the developing roller 6 through the opening 8B and the toner transfer roller 7 again together with the toner T in the toner containing portion 2.
A layer of toner T is formed by the blade 8 and is again used for development.

The toner T is separated from the toner transfer roller 7 by the net-like member 9D having such a fine mesh, and at the same time, the toner T is swept up from behind by the mixer 11 and again through the large opening 8B provided above the net-like member 8D. It can be supplied. As a result, the development history on the developing roller can be completely erased without requiring a large-scale toner recirculation mechanism as in the prior art.

For the purpose of the above description, the mesh structure of the mesh 9d is not limited to the generally known mesh structure, but can be modified in various ways. Be understood.

Further, since the contact pressure between the toner peeling member 8 and the toner transfer roller 7 similarly contributes to the peeling characteristic and the collecting ability of the toner T, it is necessary to experimentally determine the optimum value. .. Next, the blade 9 as a developer layer forming means will be described in detail.

The blade 9 is held by the first blade holder 15, the spacer 16 and the second blade holder 17. The first blade holder 15 has a shaft 18
The blade 9 is rotatably supported via the compression spring 19 and is constantly biased by a plurality of compression springs 19 for pressure so as to rotate in a predetermined direction. Is pressed against the developing roller 6.

Since the plurality of compression springs 19 are lower than the spring constant of the thin leaf spring material forming the blade 9,
Even if the contact portion of the blade 9 is worn, the pressing force hardly changes, so that a good toner layer can be maintained.

The blade 9 is provided at the tip of a thin leaf spring material 9A made of stainless steel, beryllium copper, phosphor bronze, or the like.
For example, the JIS-A hardness of silicone rubber or urethane is 3
Chip 9B made of rubber elastic body or resin of 0 to 85 degrees
Is adhered in the longitudinal direction over substantially the entire length. The tip 9B has a semicircular cross-section with a contact portion radius of about 0.5 to 6 mm, and the arcuate portion of the tip 9B is pressed against the developing roller 6 with a predetermined weight.

In this embodiment, phosphor bronze having a thickness of 0.2 mm is used as the thin leaf spring material 9A. However, depending on the shape, a material having a size of about 0.1 to 2 mm can be used. The tip 9B may be attached by any other method such as fitting or pinching, as long as it can be attached with high accuracy.

By using the support blade 9 having such a structure, the elasticity of the thin leaf spring material 9A compensates for pressure (loading) unevenness (insufficiency of accuracy), so that the movement of the developing roller 6 can be easily followed and ensured. It is possible to form a uniform toner layer. This is to make the radius of curvature of the first half of the chip 9B into an appropriate size to be a radius portion suitable for regulation of the toner passage amount, and then to the developing roller 6 in the latter half of the chip 9B.
This is because the layer of the toner T regulated in the first half can be surely charged with friction due to the contact and sliding.

The mixer 11 as the stirring means is
The function of supplying the toner T in the toner containing portion 2 to the toner transfer roller 7, and the toner T on the toner transfer roller 7 after development is scraped off by the toner peeling member 8 and then from the mesh of the toner peeling member 8. It also has a function of collecting the floating toner T in the toner accommodating portion 2, mixing it with the unused toner T, and supplying it again to the toner transfer roller 7. Next, the developing device 1 having such a configuration
The developing process will be described.

The toner T as a developer in the toner container 2 is sent to the toner transfer roller 7 while being agitated by the mixer 7, and is supplied to the developing roller 6 by the toner transfer roller 7. It A part of the toner T is attached and conveyed along with the rotation of the developing roller 6 by the mechanical conveying force of the developing roller 6 and the electrostatic force due to the charging due to friction with the surface of the developing roller 6 and other members. .. Then, blade 9
And the amount of toner T conveyed is regulated, and at the same time, the toner T is triboelectrically charged by friction between the two.

At this time, the free end of the blade 9 with respect to the developing roller 6 is in a so-called opposite position where the free end precedes the rotation of the developing roller 6. It is obvious to those skilled in the art that the present invention is not limited to this embodiment and can be used at the position of the width. Further, in the present embodiment, since the reversal development is performed using the negatively charged organic photosensitive drum 5, the negatively charged toner is used as the toner T and the blade 9 is made of a material that is easily negatively charged.

The surface potential of the photosensitive drum 5 is set to -35.
With respect to 0 to 70 V, the developing bias potential is −130 to 300 V supplied from the developing bias power source V ₂ to the metal shaft 6A of the developing roller 6 through the protective resistance 3 to 10 megohm. In this example, extremely high developing sensitivity is obtained, and a maximum density of about 1.4 is stably obtained at a surface potential of -500V and a bias voltage of 200V.

The developing roller 6 and the photosensitive drum 5 are about 1 to 1.
Contact rotation (sliding contact) is performed at a speed of about 4 times while pressing deformation to the extent that a contact width (developing nip) of about 1 to 5 mm is formed in the width direction (arrow direction) with the photosensitive drum 5.
Further, the toner T undergoes friction even at the developing position and is triboelectrically charged, so that an extremely sharp image is obtained with less fog. The undeveloped toner T ′ scrapes through the recovery blade 10 and returns to the inside of the developing device main body 4.

Next, an image forming apparatus 20 of a developing / cleaning process type (cleanerless process) using the above-described developing device 1 as a developing / cleaning device will be described with reference to FIG. In FIG. 4, a photosensitive drum 5 as an image bearing member is rotatably provided in the direction of arrow A at a substantially central portion of the image forming apparatus main body 30.

Further, around the photosensitive drum 5, along the rotation direction thereof, an erasing lamp 31 as a static eliminating means, a charging disturbing device 32 as a developer disturbing means, and a charging means, which function as described later, are sequentially provided. Is provided with a charging device 33, a laser device 34 as an electrostatic latent image forming means, a developing device as a developing / cleaning means (hereinafter referred to as a developing / cleaning means) 1 ', and a transfer roller 35 as a transfer means. There is. An image forming unit 36 is formed on the peripheral surface of the photosensitive drum 5 to form a toner image TI as a developer image. The developing / cleaning device 1'has substantially the same structure as the developing device 1 described above, but is different in the partial layer forming blade 9 and the like.

Further, in the device body 30, the device body 30
An image transfer unit 38 between the photoconductor drum 5 of the image forming unit 36 and the transfer roller 35 is provided with a paper P as a transfer target material taken out from a paper feed cassette 37 mounted on one side of the transfer roller 35. A sheet conveyance path 40 is formed which leads to the sheet ejection tray 39 arranged on the other side of the apparatus main body 1 via the sheet feeding path.

Further, the image transfer portion 3 of the paper transport path 40
On the upstream side of 8, the aligning roller pair 42 that feeds the image P taken out from the paper feeding cassette 37 via the paper feeding roller 41 and then feeds it to the image transfer unit 38 at a timely timing is provided. Are arranged. In addition, the image transfer unit 3
A fixing device 43 for fixing the toner image TI transferred onto the paper P and a paper discharge roller pair 44 for discharging the fixed paper P to the paper discharge tray 39 are provided on the downstream side of 8.
Further, between the fixing device 43 and the pair of discharge rollers 44, there is provided a gate 46 for guiding the paper P fixed by the fixing device 43 to the reverse conveyance path 45 as required.

The sheet P guided to the reversing conveyance path 45 has an image forming surface facing down through a sheet discharge roller pair 47 to a sheet discharge section 48 formed of a recess formed on the upper surface side of the apparatus main body 30. It will be ejected in this condition. Next, an image forming operation of the image forming apparatus 20 configured as above will be described.

Rotate the photosensitive drum 5 in the direction of arrow A,
The peripheral surface of the photosensitive drum 5 is corona-charged to about -500 to 800 volts by the charging charger 33. Then, the charged area is irradiated with a laser beam R from the laser device 34 to be exposed to form an electrostatic latent image on the surface of the photosensitive drum 5. Then, the electrostatic latent image faces the developing and cleaning device 1'as the photosensitive drum 5 rotates.

Here, the developing roller (hereinafter, referred to as a developing cleaning roller) 6'on which a toner T layer is formed on the peripheral surface is elastically contacted with the nip width due to the deformation, and the photosensitive drum 5 Toner T is attached to the upper electrostatic latent image to form a toner image T '. In this case, the toner T adheres to the light irradiation area and undergoes so-called reversal development. The toner T having an average particle size of 8 to 15 .mu.m is used, and due to friction with the blade 9 and the developing and cleaning roller 6 ', about -5 to 30 .mu.c / g.
It is charged to (micro coulomb / gram), and a voltage of about -1150 to -400 volts is applied to the developing and cleaning roller 6 '. The developed toner image T ′ is then conveyed to a transfer area facing the transfer roller 35.

On the other hand, in the transfer area, the paper P is taken out from the paper feed cassette 37 by the rotation of the paper feed roller 41 and is sent in synchronization with the rotation of the photosensitive drum 5 via the aligning roller pair 42. come.

The rear surface of the paper P is charged to a positive polarity by the transfer roller 35. Therefore, the toner image T'on the surface of the photosensitive drum 5 is electrostatically charged on the paper P.
Is transferred to and transferred to. Here, the rotating shaft of the transfer roller 35 is 1000 to 20
A voltage of 00 volt is applied, and the silicone resin provided on both ends of the transfer roller 35 is supplied with 15 to 40% by weight of conductive carbon, and the conductive resin is applied to the surface of the transfer roller 35.
^Five -10 ⁹ A voltage is applied to the conductive surface of Ω · cm.

As for the rubber hardness of the transfer roller 35 as a whole, the one having a softness of 25 to 50 ° according to the comparative measurement of JIS method has a wide tolerance of the pressing force of the transfer roller 35 to the photosensitive drum 5 and is good. It was Further, the transferred paper P is sent to the fixing device 43, where the toner T is melted and fixed on the paper P, and then discharged.

By the way, on the surface of the photosensitive drum 5 after the transfer, a small amount of the toner T left without being completely transferred or the positive and negative electrostatic latent images left after the transfer of the toner T remains. ..

The toner T or the electrostatic latent image is first erased to a negative latent image by the erasing lamp 31, and the residual toner T is small, but it is not always necessary, but preferably, the electrostatic disturber 32. It is transported to and disturbed and unpatterned.

In the charging disturbing device 32, the elastic brush 32A is brought into contact with the electrostatic latent image to exert a mechanical and electrostatic force so that the electrostatic brush 32A is finely divided into an unreadable state. Disturb the latent image. In this case, a voltage (about 400 V or more) sufficient to inject charge into the toner T is applied so that the remaining toner T is not adsorbed from the surface of the photosensitive drum 5, and the toner T once adsorbed is repelled again. It is adjusted to go out.

In this way, the afterimage is disturbed, and most of the toner T is scattered on the surface of the photosensitive drum 5 and adheres thereto, but hardly accumulates in the charging disturber 32. That is, the charge disturbing device 28 does not have a function as an electrostatic recording device, but has an auxiliary function. The toner T scattered on the surface of the photosensitive drum 5 is distributed in a sufficiently small mist state, and no longer has information as characters or images. The disturbed area is then conveyed to the charging position facing the charging charger 33,
It is piled up from above and charged with corona. After charging, the electrostatic latent image is formed by being exposed by the laser device 34, and again reaches the developing and cleaning position facing the developing device (developing and cleaning device) 1 '(second time).

In this case, in the electrostatic latent image formed in the second time, even in the exposed portion (image portion to which toner should adhere) and the non-exposed portion (non-image portion), the roller transfer greatly reduces. In addition, since the residual toner is substantially evenly and sufficiently thinly scattered in advance, exposure unevenness does not occur.
Therefore, even in the second development, the residual potential after exposure becomes uniform, so that a uniform toner image can be obtained.

Here, the cleaning developing roller 6'has an elasticity of 30 to 70 ° in accordance with the JIS rubber hardness measuring method and is 10 ² as described above for the developing roller 6. ~ 10 ⁸
Since it has the electric conductivity of, a load of 20 to 150 g / cm is applied as a linear load to the cleaning and developing roller 6'and 1.5 to
By pressing and sliding with a speed difference of 4 times,
A contact width (nip) of mm is generated, and in this nip, the residual toner T and the toner T on the cleaning and developing roller 6'are disturbingly slidably contacted with each other, so that a strong frictional force is generated and the cleaning ability is enhanced. However, since the developer is formed only by the toner T, no image quality deterioration such as streaks or sweeps occurs.

Further, in the non-exposure portion, the toner T adhering in order that the attraction force by the developing bias exceeds that of the photosensitive drum 5 is successively developed by the developing device (developing and cleaning device).
1'is attracted and collected. That is, by applying a developing bias having a value between the residual potential of the exposed portion and the potential of the non-exposed portion to the cleaning and developing roller 6 ', new toner T is discharged from the developing and cleaning roller 6'to the exposed portion. The residual toner T that adheres to the non-image area at the same time
From here, it is attracted to the developing cleaning roller 6'and collected. In this case, since the residual toner T is small and dispersed in the charging disturbing device 32 in the form of a small mist in advance, the developing and cleaning device 1'can efficiently collect the residual toner T, resulting in defective collection. Never.

In this way, the photosensitive drums 5 are rotated in an overlapping manner and used in duplicate to obtain one recorded image. Then, after development and cleaning, the toner image T ′ is transferred onto the paper P at a position facing the transfer roller 35. Hereinafter, similar steps are repeated.

On the other hand, in the developer T collected by the developing and cleaning roller 6 ', the paper powder separated from the paper P at the time of transfer and attached to the photosensitive drum 5 is also collected. The paper powder is generally mixed with talc of about 2 to 8 microns and an additive of a mineral substance called kaothin, and when these are collected together with the toner T by the developing and cleaning roller 6 ', the developing and cleaning roller 6'is then collected. Is slidably contacted with a toner transfer roller 7 which is an intermediate roller which makes rotational contact with each other as indicated by an arrow.

The toner transfer roller 7 has the same shape and function as the toner transfer roller 7 described above. However, when it is used as the developing and cleaning device 1 ', the toner T in the toner hopper 3 is removed from the developing and cleaning roller 6'during the developing and cleaning operation.
The bias voltage for the toner transfer roller 7 for carrying the toner to the side is set to be higher by 50 to 200 V (in absolute magnitude) than the developing and cleaning roller 6 ', whereby the supply of the toner T is accelerated and the image density is increased. We are trying to maintain high.

On the other hand, at the time of so-called non-image formation or between images, such as the feeding interval of the paper P and the paper discharging process, the toner T is surely discharged from the developing cleaning roller 6 '.
The bias voltage applied to the toner transfer roller 7 in order to transfer and separate paper dust and paper dust to the toner transfer roller 7 side is 0 to 10
Switch at 0 volt lower (absolute value). In this way, the toner T and the paper powder which could not be peeled off by mechanical peeling are also collected by the toner transfer roller 7.

Toner T accumulated on the toner transfer roller 7
Conventionally, the toner was left as it is, but in the present invention, as described above, the toner peeling member 8 is used as a toner.
The transfer rollers 7 are peeled off one after another. Peeled toner T
The toner is sent to the toner accommodating portion 2 and then mixed with the toner T in the toner accommodating portion 2 by the mixer 11. At the same time, the bias of the toner transfer roller 7 is switched, and at the same time, the toner is re-energized. It is conveyed from above the transfer roller 7 and supplied to the developing cleaning roller 6 '.

The above-described arrangement of the bias power supplies is performed in the same arrangement as the bias power supplies V ₁ and V ₂ applied to the developing device 1 described above. The power source corresponding to V ₁ is −0 to −400 V according to the image forming process described above,
Most preferably it was most effective when switched to -100 and -300 volts. It should be noted that this is when the developing bias V ₂ is −200 V, and it is needless to say that when the developing bias is changed, it is necessary to change so as to keep the potential difference relatively as described above. Absent.

The toner T or the mixed foreign matter collected as described above is once collected in the toner accommodating portion 2 without being accumulated in the developing / cleaning roller 6'and mixed with the unused toner T to be reused later. Since the history of the developing and cleaning roller 6'is erased and the history difference of the toner T in the developing and cleaning device 1'is also eliminated, the image sharply changes from a certain point in time as in the conventional case. It is possible to prevent image defects due to the difference in the history of the developers in the developing container, which may cause unevenness or unevenness.

Further, by sliding the net-like body 8D made of ultrafine fibers or the like as the toner peeling member 8 against the toner transfer roller 7, the toner can be peeled with a lighter frictional force than in the conventional means. Since it is easy to provide a rotating body such as the mixer 11 from behind the mesh body 8D in the vicinity of the contact portion,
It is easy to mix the toner T that has been peeled off and floated from the mesh with the unused toner T as it is.

Further, in the developing device using an elastic member such as rubber, which has a drawback that it is mechanically vulnerable, although the toner transfer roller 7 has excellent transport characteristics, mechanical stress is particularly reduced. By using the toner peeling member 8 according to the present invention, it is possible to extend the life.

Although the developing device 1 of the present invention is applied to the image forming device 20 of the cleanerless process type in which the developing process and the cleaning process are performed at the same time in the above-mentioned embodiment, it has been explained. Alternatively, as shown in FIG. 5, even in an image forming apparatus including a cleaner 60 as a cleaning device and performing a developing process and a cleaning process separately,
It can be used without any change. In the description of FIG. 5, the same parts as those in the above-described embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. In addition, it goes without saying that the present invention can be variously modified without departing from the scope of the invention.

[0086]

According to the developing apparatus of the present invention, the developer on the developer conveying means that has not been used for development is once removed and collected in the developer accommodating portion, so that the developer layer forming means is short-circuited. Without being conveyed to the side, the development history on the developer conveying means can be completely erased, and a good developing operation without developing failure called a sleeve ghost can be performed.

Even if foreign matter such as paper dust separated from the transfer paper is mixed with the developer and collected in the developing device, the foreign matter is collected together with the developer in the developer accommodating portion and accumulated in the developer conveying means. This prevents the developer layer forming device from normally charging the developer, and prevents the device from being replaced or cleaned due to an image defect even though the developer remains. It Therefore, there is an effect that it can be applied to a developing / cleaning process (cleanerless process).

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a developing device of the present invention.

FIG. 2 is a perspective view showing a cross section of a part of a developing roller of the developing device shown in FIG.

FIG. 3 is a perspective view showing a configuration of a toner peeling member of the developing device shown in FIG.

FIG. 4 is a front view schematically showing the internal configuration of a cleanerless process type image forming apparatus to which the developing device shown in FIG. 1 is applied.

5 is a diagram schematically showing a main part of a process type image forming apparatus with a cleaner to which the developing device shown in FIG. 1 is applied.

[Explanation of symbols]

T ... toner (developer), T '... development residual toner, 1 ... developing device, 1' ... developing device also used for developing and cleaning (developing and cleaning device), 2 ... toner accommodating portion (developer accommodating portion), 4 ... Developing device main body, 5 ... Photosensitive drum (image bearing member), 6 ... Developing roller (developer conveying means), 6 '... Developing roller also used for developing cleaning (developing cleaning roller), 7 ... toner transfer roller (developer transfer means), 8 ... toner release member (developer release means), 8A ... film member, 8B ... opening, 8C ... opening, 8D ... mesh body, 9 ... blur (Developer layer forming means).

 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Adult Yoshida 70 Yanagi-cho, Sachi-ku, Kawasaki City, Kanagawa Prefecture, Toshiba Yanagimachi Co., Ltd. (72) Minor Yoshida 70, Yanagi-cho, Sachi-ku, Kawasaki, Kanagawa Prefecture (72) Inventor Koji Hirano 70, Yanagicho, Saiwai-ku, Kawasaki-shi, Kanagawa Toshiba Intelligent Technology Co., Ltd.

Claims (2)

[Claims] 1. A developing device which also serves as a cleaning device for visualizing a latent image on an image bearing member with a one-component developer and for cleaning a residual developer on the image bearing member, wherein the one-component developer is accommodated. A developing device main body having a developer accommodating portion, arranged in the developing device main body so as to face the developed portion of the image carrier, and supplies the developer to the developed portion during the developing process and the cleaning unit during the cleaning process. Rotatably drivable developer conveying means for receiving the residual developer on the image carrier, developer layer forming means for forming a thin layer of the one-component developer on the surface of the developer conveying means, and the developing device main body And a developer transfer means rotatably provided therein for supplying the developer in the developer accommodating portion to the developer transporting means and receiving the developer on the developer transporting means which has passed through the developed portion. State of contact with agent transfer means A developer peeling means for the developer attached to the developer transfer means provided peeled over a predetermined effective length to recover to the developer containing portion, formed by including the. 2. A developing device for visualizing a latent image on an image carrier by a one-component developer, the developing device main body having a developer accommodating portion for accommodating the one-component developer, and inside the developing device main body. Further, a developer transporting unit that is arranged so as to face the developed portion of the image carrier and that can supply the developer to the developed portion, and a rotationally drivable developer transporting unit, and a surface of the developer transporting unit of the one-component developer A developer layer forming means for forming a thin layer, and a developer which is rotatably provided in the developing device main body and supplies the developer in the developer accommodating portion to the developer conveying means and which has passed through the developed portion. The developer transfer means for receiving the developer on the conveying means, and the developer attached to the developer transfer means provided in contact with the developer transfer means, are peeled off over a predetermined effective length, and the developer is transferred. A developer peeling means for collecting in the accommodating portion Equipped with a composed.